1. Technical Field
The present invention relates to apparatus including a manifold for automatically administering intravenous solutions and medications. More particularly, the invention relates to apparatus for sequentially supplying a plurality of solutions to a single intravenous tube.
2. Prior Art
Medical treatment frequently requires the administration of more than one solution or medication by intravenous injection. In many medical treatments several drugs are administered periodically.
To minimize the number of injections given to a patent it is common practice to inject medications through a single intravenous tubing by means of one or more Y-connectors. The normal procedure is for a member of a hospital staff to unsheath a needle and insert it in a Y-connector at time periods and in quantities specified by the treating physician. When a given medication has been administered the needle is removed from the Y-connector, resheathed and stored next to the patient's bed until the next treatment interval. This procedure is subject to contamination due to the repeated sheathing and unsheathing of the needle. While this procedure is acceptable when a limited number of medications are administered, as the frequency of administration increases the amount of staff time expended, difficulty of keeping the needle and Y-connector sterile, and chance of error in administering a medication likewise increase.
This procedure for periodically administering medications to patients is time consuming for hospital staff and requires detailed instructions because medication is often prescribed around the clock. In medical treatments requiring a large number of solutions each having a loosely hanging tube, a member of the hospital staff could conceivably be confused and dispense the wrong solution.
Frequently, tubes are left dangling loosely around the patient's bed, instead of being tied out of the way, because the tubes must be free for connection to the Y-connector. The tubes can be caught in the side rails of the bed and damaged. During administration of a solution one of the tubes may be pinched off inadvertently resulting in insufficient medication being dispensed.
Various types of manifolding apparatus having been developed to meet the problems posed by supplying multiple medications to a patient. U.S. Pat. No. 2,954,028 to Smith discloses such an apparatus for administering parenteral fluids through the use of a manifold. While the Smith manifold allows a large number of medications to be administered simultaneously, it is bulky and time consuming to set up. The different medications in the various passages of the manifold may intermix and if not compatible could interact deleteriously with each other. Different branches of the manifold open into the central tube at directly opposite locations which allows the fluids to flow from one branch into another.
Reuse of the Smith manifold is subject to several drawbacks. It is well known that some medications, while theraputic for some, are toxic to other patients. If a patient receives medication through a manifold residual deposits of a previously administered medication may be present in the manifold. If the residual deposit is a substance that is toxic to the patient it is possible that the patient could be harmed. Therefore, unless the manifold is cleaned and sterilized between each patient, there is a danger that a patient may inadvertently receive residue from a medication administered to a prior patient. Cleaning and sterilizing the manifold between uses is laborious and requires valuable staff time.
In addition, prior art devices have failed to disclose an accurate method for sequentially metering several different medications through a common catheter that is both inexpensive and simple to use. While visual sight glass drop counters have been used with Y-connectors, as shown in U.S. Pat. No. 3,886,937 to Bobo et al and in the Smith manifold described above, such devices are time consuming to use and must be visually monitored for accuracy. Electronic drop counters as disclosed in U.S. Pat. No. 4,094,318 to Burke offer improved accuracy but are extremely expensive, expecially if more than one or two solutions are to be administered.